(1) Field of the Invention
The present invention relates to a refrigerant relief device, and more particularly to a refrigerant relief device which is mounted in a refrigeration cycle for an automotive air conditioner using a gas dangerous to a human body as refrigerant.
(2) Description of the Related Art
A typical automotive air conditioner comprises a compressor for compressing refrigerant circulating through a refrigeration cycle, a condenser for condensing the compressed refrigerant, a receiver/dryer for separating the condensed refrigerant into a gas and a liquid while temporarily storing the refrigerant circulating through the refrigeration cycle, an expansion device for restricting and expanding liquid refrigerant separated by gas/liquid separation, and an evaporator for evaporating the expanded refrigerant and returning the same to the compressor.
Although in the refrigeration cycle for an automotive air conditioner, a CFC substitute (HFC-134a) has been used as refrigerant, refrigerant with a small global warming potential has been demanded to be used from the viewpoint of global warming. As such refrigerant, there are considered e.g. carbon dioxide, HFC-152a, butane, and propane.
However, when these substances are used as refrigerant for an automotive air conditioner, if an evaporator or piping disposed in a vehicle compartment is broken to cause refrigerant release into the vehicle compartment, there is a danger of suffocation due to oxygen deficiency in the case where refrigerant is carbon dioxide, whereas in the case when refrigerant is an inflammable gas, such as HFC-152a, there is a danger of occurrence of a fire. These can have serious adverse influence on occupants.
To overcome the above problems, it is necessary to prevent refrigerant in the refrigeration cycle from releasing into the vehicle compartment, e.g. when a crack is produced in the evaporator by aging thereof, or even when components of the refrigeration cycle are seriously damaged e.g. by a collision accident.
An example of proposal to this end is to mount relief devices in advance on the respective high-pressure side and low-pressure side of the compressor of the automotive air conditioner using inflammable refrigerant, and when there occurs a collision accident to cause an airbag to be operated, operate the relief devices for releasing the inflammable refrigerant in the refrigeration cycle to the outside of the vehicle compartment (see e.g. Mahmoud Ghodbane, Ph.D., James A. Baker, William R. Hill, and Stephen O. Andersen, Ph.D., ‘R-152a Mobile A/C with Directed Relief Safety System’, pages 4 and 13. [online]. SAE(The Society of Automotive Engineers), 2003 Alternate Refrigerants Systems Symposium presentations Aug. 1, 2003. [retrieved on Mar. 12, 2004]. Retrieved from the Internet: <URL:http://www.sae.org/altrefrigerant/presentations/presw-hill.pdf>).